Already known in the prior art are shipment tracking methods and notably mail tracking methods based on bar codes. FR 2 715 333 pertains to a printing method for postal envelopes, and more precisely the printing of the final destination of a postal envelope by means of a bar code. Also known is WO 96/13803 which pertains to a method for labeling mail with bar codes with each bar code having at least four parts. Two different parts indicate the beginning and the end of the code. A content indicator, which follows the beginning bars, indicates the structure and the length of the following data field so that it will be read correctly. The data field can contain a postal code, with or without address information, information on the client, etc.
Use of bar codes is also known in the field of shipping and transport for identification of a shipment. This technique is based on the assignment of a bar code to a shipment and an association of the bar code with the shipment by a database. Reading the bar code at different sites as the shipment advances makes it possible to track the advancement of the shipment. Part of the information relative to the advancement of the shipment is made available to the shipper in a database that it can consult.
A major disadvantage of this technique is that it requires a very large number of bar codes to allow identification of each shipment.
Furthermore, since assignment of bar codes to the shipments is made in a random manner, it is necessary to have available a very large database permanently containing all of the possible bar codes according to the desired configuration and powerful data processing means, which limits the use of the technique to valuable shipments, i.e., essentially packages and registered mail.